Deep‐Red InP Core‐Multishell Quantum Dots for Highly Bright and Efficient Light‐Emitting Diodes

Abstract InP‐based quantum dots (QDs) are one of the most promising heavy‐metal‐free materials for light‐emitting applications to substitute cadmium‐analogous QDs. With a bulk band gap of 1.35 eV, InP QDs can be made to emit light in the deep red and even near‐infrared region by adjusting the size. Deep‐red light‐emitting diodes (LEDs) are of great interest for promoting the growth of plants and accurate red LED displays. However, the synthesis and the fabrication of InP‐based quantum‐dot LEDs (QLEDs) emitting in the deep red region are still under development. Here, the study reports deep‐red InP/ZnSe/ZnSeS/ZnS core‐shell QDs with a photoluminescence (PL) emission peak at 680 nm and a PL quantum yield up to 95%, which is the highest among reported deep‐red QDs. Multi‐shell with a transition layer of ZnSeS is realized to decrease the lattice mismatch in the shell and increase the shell thickness, which efficiently confines charge carriers and reduces non‐radiative recombinations. In addition, the core‐shell InP QLED achieves a high luminescence of 2263 cd m⁻² and an external quantum efficiency up to 6.5%. This report provides a new strategy for promoting the development of deep‐red QLEDs for next‐generation lighting and display devices.